Rubber tear strength tests

ISO 34-1 2004 Rubber, vulcanized or thermoplastic - Determination of tear strength -Part 1 Trouser, angle and crescent test pieces... 

Neoprene is the generic name for polychloroprene rubber. It has been produced commercially since 1931 and had rapid and wide acceptance because it is much superior to natural rubber for heat and oil resistance. Heat resistance is far better than NR, BR or SBR. but less than EPDM. When heated in the absence of air, neoprene withstands degradation better than other elastomers which are normally considered more heat resistant, and retains its properties fifteen times longer than in the presence of air. Compression set at higher temperature is better than natural rubber and 100°C is typically the test temperature rather than 70°C. Abrasion resistance is not as good as natural rubber but generally better than most heat resistant and oil resistant rubbers. This is also true for tear strength and flex resistance. 

Part 1 Trouser, angle, and crescent test pieces Part 2 Small (delft) test pieces Standard test method for tear strength of conventional vulcanized rubber and thermoplastic elastomers Testing of rubber and elastomers Determination of the tear strength of elastomers Trouser test piece... 

Physical testing of rubber part A3 Determination of tear strength [trouser, angle, and crescent test pieces Section 3.2 Small (Delft) test pieces... 

Figure 7. Effect of the pyrolysis temperature on physical properties (a) — (g) of rubber vulcanizates (MP test) (a) tensile strength (b) elongation (c) 300% modulus (d) tear strength (e) hardness (f) cut growth (g) abrasion. Test recipe of rubber compounds is the same as in Table III (Q) 15 (A) 20 ( 3>) 30 (ffz) 4 ...

The strain rates and temperatures prevailing in abrasion are very different from those used in routine laboratory testing of tensile or tear strength. Because of friction, local temperatures may far exceed those of the test track or of the bulk of the rubber (229-230). Even at small sliding velocities the effective strain rate is very large, as small volume elements of rubber are deformed repeatedly to high strains by the many surface... 

Other standards similar to the above are as follows. ISO 34. 1994 (= BS 903 A3, 1995). Rubber, vulcanized or thermoplastic -Determination of tear strength. Part 1. TroiKser. angle and crescent test pieces. ISO 816, 1983. Rubber, vulcanized Determination of tear strength of small test pieces (Delft test pieces). Here, the force required to tear across the width of a small test piece (2 x 9 x 60 mm) containing a 5 mm wide slit in the center of the specimen is measured. 

The existing test standards on the resistance of these materials to crack propagation concentrate on determining the tear strength values. Some of these standards arc specific to plastics film and sheeting [202 208], fabrics coated with rubber or plastics [209-212]. non-woven textile fabrics [213-216], and woven textile fabrics [217-218]. 

The tear resistance (sometimes also called tear strength) is a more or less technological material parameter which should describe the resistance of the material against the growth of a sharp cut. Usually, tear tests are applied for rubber mixtures, mbber vulcanizates, thermoplastic films, leather or textiles. Different standards exist for the determination of the tear resistance for elastomers and thermoplastic films, for example ... 

Standard test method for tear strength of craiventional vulcanized rubber and thermoplastic elastomers... 

Here v represents the Poisson ratio, defined as the ratio between the linear contraction and the elongation in the axis of stretching. In the case of constant volume (an incompressible body like rubber), i> = 0.5 and therefore E = 3G for rigid materials p < 0.3. There is also a direct test for tear strength, mainly in the case of thin films, similar to those used in the paper industry. 

Standard Test Method for Tear Strength of Conventional Vulcanized Rubber and Thermoplastic Elastomers. 

The Lambda series of Medicaflex is a polyurethane-based TPE polymer that exhibits low modulus characteristics with high tear strength and abrasion resistance. Those listed in the tables have passed USP Class VI compatibility tests and have been used as replacements in some natural rubber latex and silicone rubber applications. The polymer has been applied to uses such as catheters, tubing and films where softness, low durometer hardness, low modulus or high elongation are needed (Tables 4.3, 4.12, and 4.13). 

D 395 Test Method for Rubber Property - Compression Set D 412 Test Method for Vulcanized Rubber, Thermoplastic Rubbers and Thermoplastic Elastomer - Tension D 471 Test Method for Rubber Property - Effect of Liquids D 570 Test Method for Water Absorption of Plastics D 624 Test Method for Tear Strength of Conventional Vulcanized Rubber and Thermoplastic Elastomer D 638 Test method for Tensile Properties of Plastics D 792 Test Method for Specific Gravity (Relative Density) and Density of Plastics by Displacement... 

Table 5.8 summarizes data from the patent. Tests were made in natural rubber at a loading of 60 parts by weight of filler per 100 parts of rubber using 3% sulfur and an optimum amount of accelerators benzothiazyl disulfide and thiuram M and optimum cure time, usually for highest tear strength. 

---